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1 January 2011 Clustering of optically trapped large diameter plasmonic gold nanoparticles by laser beam of hybrid-TEM11* mode
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Multiple trapping and clustering of gold nanoparticles (Au-NPs) of 254- and 150-nm diameter was affected using optical tweezers near the plasmon excitation wavelength. To ensure that the gradient force exceeded the sum of multiply-enhanced destabilizing absorption and scattering forces originating from plasmon excitation, embedded intensity gradient regions of a spatially featured asymmetric (SFA) laser beam were exploited. Thus, an intra-cavity generated SFA beam, also referred as hybrid TEM11* mode, is an intermediate between pure TEM00 and TEM11 beams and was directly obtained from a diode-pumped solid state (Nd:YAG) laser resonator without introducing any external beam modulation devices. The parabolic Gaussian-ray model of a tightly focused laser beam was adopted to evaluate the radiation forces including the volume-correction factor raised from fractional polarization of such large diameter Au-NPs under laser illumination. Temperature rise of Au-NPs and its dissipation profile in surrounding medium has also been presented. This multiple trapping and clustering of Au-NPs at plasmon excitation wavelength using sufficiently low power could be realized due to embedded intensity gradients of the SFA beam. The study might be useful for understanding the light-matter interaction, improving the sensitivity of diagnostics, and safety and efficacy of therapeutic nanotechnologies in medicine, photothermolysis, and surface-enhanced Raman spectroscopy, etc.
© 2011 Society of Photo-Optical Instrumentation Engineers (SPIE) 1934-2608/2011/5(1)/053511/17/$25.00
Ranjeet Kumar, Dalip S. Mehta, and Chandra Shakher "Clustering of optically trapped large diameter plasmonic gold nanoparticles by laser beam of hybrid-TEM11* mode," Journal of Nanophotonics 5(1), 053511 (1 January 2011).
Published: 1 January 2011

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